The Hawke's Bay District Health Board is yet to confirm whether the contaminated Havelock North water contributed to the death of a retirement home resident.
On Saturday the DHB chief executive Kevin Snee said a person had died, but could not confirm the death was caused by drinking contaminated water.
"We've seen eight quite unwell patients in one residential care home, and we've also, over the last 24 hours, had a death in a nursing home which may or may not be related to this problem, but is the consequence of a gastric-like illness."
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Hastings mayor Lawrence Yule said the source of the gastroenteritis the person had was unclear because there had been outbreaks of airborne disease that could have caused it.